1. Field of the Invention
This invention relates to electrical conductors, and more particularly, to washable, painted-on electrical conductors and a method for making such conductors with varying resistances.
2. Description of the Related Art
Fabric-enclosed toys for young children are popular and well-known. Such toys may contain layers of fabric, foam rubber, or the like, to make the toys soft and flexible. In addition, with the advent of low-cost electronic circuitry, it has become popular to place such circuitry in toys to make them responsive to the child in various ways. Sound synthesis circuitry, for example, has been used in many toys to make sounds when a switch is activated.
The electronic circuitry used in many such toys includes a discrete switch connected to an electronic circuit board by wires. In some instances, switches made out of plastic sheeting with a hard backing have been used. While these switches can be advantageous in many plastic toys, they are less advantageous when used in a soft toy such as a stuffed animal because the switch often creates hard lumps that detract from the toy's soft ambience. Instead, it is desirable to employ an electronic switch that accents the humanistic aesthetics so essential to a successful soft toy.
Because soft toys inevitably become soiled, it is advantageous for these toys to be fully washable. Soft toys containing electronic switches have, in the past, only been surface washable. Even after removing batteries and electronics from traditional soft toys, washing would permanently damage the remaining unremovable switches and wiring.
Historically, electronic toys have had a high return-for-repair rate. This problem often occurs because of wiring that has become inflexible. Stress points often occur near solder points. In a soft toy, it may take only a few bends before the wire breaks. Thus, there is a need for a wiring system that is inherently flexible and does not require soldering. Such wiring should also be easy to connect with electronic assemblies and inexpensive to manufacture. The wiring should be non-toxic, and should be safe for use in toys for small children such that it avoids the possibility of strangulation. In addition, the wiring should provide low resistance, even after being washed several times.
Additionally, in all electrical circuits it is advantageous to employ conductors of varying resistance in order to direct and control current flow within the circuit. Historically, electronic toys have had to incorporate hard electrical components (such as resistors) within the electric circuits to accomplish this function, thus reducing the toy's humanistic appeal and its ability to be washed. As it is possible for a child to swallow a small part upon its accidental separation from the toy, such components also present safety risks. If such components are used in electronic toys, they should be washable, soft, non-toxic and safer as should be the electric wiring.